為什麼可以create dir ,但是卻無法login 該目錄

[watermelonyu]

下列是我的問題,我用system user login

去create 一個目錄 ,SET DEF 卻告訴我

directory not found

但是到實體目錄touch 一個檔案後就可以login了,請問這是為什麼呢?

Welcome to OpenVMS (TM) Alpha Operating System, Version V7.3-2



Username: system

Password:

Welcome to OpenVMS (TM) Alpha Operating System, Version V7.3-2

Last interactive login on Thursday, 12-APR-2007 17:43:51.80

Last non-interactive login on Thursday, 12-APR-2007 17:24:07.97

$ sh def

SYS$SYSROOT:

= SYS$SYSROOT:

= SYS$COMMON:

$ create/dir

$ dir test123.dir



Directory SYS$SYSROOT:



TEST123.DIR;1



Total of 1 file.

$ set def

$ dir

%DIRECT-E-OPENIN, error opening SYS$COMMON:*.*;* as input

-RMS-E-DNF, directory not found

-SYSTEM-W-NOSUCHFILE, no such file



$ set def sys$sysdevice:

$ dir test123.dir



Directory SYS$SYSDEVICE:



TEST123.DIR;1



Total of 1 file.

$ set def

$ dir

%DIRECT-W-NOFILES, no files found

$ copy nl: test123.log

$ dir



Directory SYS$SYSDEVICE:



TEST123.LOG;1





Welcome to OpenVMS (TM) Alpha Operating System, Version V7.3-2



Username: system

Password:

Welcome to OpenVMS (TM) Alpha Operating System, Version V7.3-2

Last interactive login on Thursday, 12-APR-2007 19:29:58.88

Last non-interactive login on Thursday, 12-APR-2007 17:24:07.97

$ set def

$ dir



Directory SYS$SYSROOT:



TEST123.LOG;1



Total of 1 file.

[watermelonyu]

這是因為 directory path 使用了 logical name search list.

不同的 DCL 命令在處理 logical name search list 時若遇到 exceptions 會有不同處理方式!



The logical name SYS$SYSROOT is defined as a search list that points first to

a local root (SYS$SYSDEVICE:) and then to the common root

(SYS$COMMON:). Thus, the logical names for the system directories

(SYS$SYSTEM, SYS$LIBRARY, SYS$MANAGER, and so forth) point to two

directories.



$ sh def

SYS$SYSROOT:

= SYS$SYSROOT:

= SYS$COMMON:

$ sh log SYS$SYSROOT

"SYS$SYSROOT" = "A800$DKA0:" (LNM$SYSTEM_TABLE)

= "SYS$COMMON:"

1 "SYS$COMMON" = "A800$DKA0:" (LNM$SYSTEM_TABLE)

$ sh log sys$sysdevice

"SYS$SYSDEVICE" = "A800$DKA0:" (LNM$SYSTEM_TABLE)

$



$! test.dir will be created in the first directory in the logical name search list,

$! in this case it is created in A800$DKA0:

$ create/dir



$! dir looks at both directires, found one test.dir

$ dir test.dir



Directory SYS$SYSROOT:



TEST.DIR;1



Total of 1 file.

$ set def

$ sh def

SYS$SYSROOT:

= SYS$SYSROOT:



$! dir look at A800$DKA0: first but no file found,

$! it then continue look at SYS$COMMON: but found

$! the directory does not exist, so it complains.

$ dir

%DIRECT-E-OPENIN, error opening SYS$COMMON:*.*;* as input

-RMS-E-DNF, directory not found

-SYSTEM-W-NOSUCHFILE, no such file

$



$! ed will check if test.log already exist. Because no file found in

$! A800$DKA0:, it continue look at

$! SYS$COMMON: but found the directory does not exist, so it complains.

$ ed test.log

%EDT-F-OPENIN, error opening SYS$COMMON:TEST.log; as input

-RMS-E-DNF, directory not found

-SYSTEM-W-NOSUCHFILE, no such file

$



$! No problem for the copy